748 EXPERIMENT STATION RECORD. 



pieces all heads, stems, and leaves, and burning by means of crude petroleum ; 

 (3) liming or watering the hole before replanting, and dipping the new piece 

 to be planted in a weak solution of copper sulphate; (4) burning the entire 

 section and replanting away from the old stools; (5) importing suckers from 

 uoninfected farms and other banana countries; (6) isolating diseasetl sections 

 with trenches 2 ft. wide and 2i ft. deep, filling with dry trash, and bux-ning; and 

 (7) spading, forking, clean weeding, and trenching. 



The disease does not attack other crops, such as cassava, cowpeas, corn, 

 cacao, and rublxM", even when grown on land badly infected with the disease. 



A banana disease due to nematodes, G. Korff {Prakt. BI. Pflnnzcnhau u. 

 Srhutz, n. scr., 8 {1910). ISio. 6', pp. 61-67. figs. S). — A description is given of a 

 banana disease, usually of greenhouse plants, caused by the nematode Hcterodera 

 radicicola, accompanied by the usual directions for controlling this disease. 



Cacao canker (Agi: Xeics [Barhados], 9 {1910), No. 2U, pp. 222, 228).— A 

 general discussion as to the causes of this disease is given, in which the claim 

 made by J. B. Rorer in a recent article (E. S. R., 23. p. 549, and below) that 

 cacao canker of the branches and pods is the same disease and is due to 

 l'Ji!/tit])litli()r(i omniront is especially noted. 



Observations on the black rot of pods and the tree canker of the Alligator cacao 

 indicate that in Dominica as in Trinidad the canker disease is due to P. omni- 

 rora. It is claimed that some varieties of cacao are highly susceptible to this 

 disease, while others are practically immune. 



In addition to the usual remedies for controlling this disease, spraying with 

 Bordeaux mixture is recommendetl. 



Pod rot, canker, and chupon wilt of cacao caused by Phytophthora sp., 

 J. B. RoRias {Bill. Dcpt. Agr. Tiiniihul. <) (1910). Ao. 6'J. pp. 79-10.i).—ln this 

 report on tree canker and i)Od rot of cacao, the author gives the history of the 

 diseases in various countries where cacao is grown, the conclusions reached as 

 to their cause by previous investigators, and a summary of the facts concerning 

 these diseases as brought out by a study of the literature on the subject. The 

 characteristics of pod rot, canker, and chupon or sprout wilt, sources of infec- 

 tion, losses caused by these diseases, other fungi associated with them, cultural 

 studies, life history of cacao Phytophthora, inoculation experiments with it, pre- 

 ventive measures, and recommendations as to its control are also considered. 



As a result of a study of the literature on the subject, and his own invc^stlga- 

 tions of the diseases, the author maintains that the jiod rot and tree canker of 

 cacao are probably identical in all parts of the world where cacao is grown, that 

 they are primarily due to the fungus Phiftophiliora sp., and that the various 

 species of Nectria, Calonectria. etc.. are not the cause of this disease, but only 

 secondary invading saprophytes. 



It is stated that probably the cankers on the trees came from the fungus in the 

 pods working its way back into the cushion and from there into the bark, 

 and thence by strands of mycelium spreading to other areas in the inner bark 

 of the tree. 



The pod rot may originate in two ways, either by spore infection on the surface 

 of the pod, which is the usual method, or by strands of mycelium from a canker 

 penetrating through the stem of the pod into the pod itself. A wilt disease of 

 the chupons is also ascribed to the same fungus. Infection occurs mainly during 

 the rainy season from diseased pods, and the disease is kept going month after 

 month, as pods are always on the trees. 



In inoculation experiments with pure cultures of the various fungi found 

 associated with canker and pod rot, only the. Phytophthora was successful in 

 producing infec-tion on healthy pods with all tlie characteristics of the disease. 

 Another fungus (Diplodia cacaoicola) was found capable of attacking healthy 



